Helium, standard state pressure

EXAMPLE 11.6 The standard state pressure of helium. To calculate for helium at T = 300 K, first use Equation (11.19) to get... 

Standard enthalpy (heat) of formation The standard state of a substance is the normal state of the substance at 298 K (25 °C) and one atmosphere pressure. For example, the standard state of water is a liquid, whereas the standard state of helium is a monatomic gas. The change in enthalpy that accompanies the formation of one mole of a compound in its standard state from its constituent elements in their standard states is called the standard enthalpy (heat) of formation (A/f ) of the compound. For example, the standard heat of formation for magnesium oxide is given by this equation. 

What would be the difference (if any) in the weights of two basketballs, one filled with air and one filled with helium Please give your answer in grams. Assume the standard basketball has a diameter of 9.0 in. and is filled to a pressure of 8.0 lb/in.2 Sorry for the English units, but after all basketball was invented in the United States. 

The values in these tables were generated from the NIST REFPROP software (Lemmon, E.W., McLinden, M.O., and Huber, M.L., NIST Standard Reference Database 23 Reference Fluid Thermodynamic and Transport Properties—REFPROP, National Institute of Standards and Technology, Standard Reference Data Program, Gaithersburg, Md., 2002, Version 7.1). The primary source for the thermodynamic properties is McCarty, R.D., and Arp, V D., A New Wide Range Equation of State for Helium, Ado. Cryo. Eng. 35 1465-1475,1990. The source for viscosity is Arp, V. D., McCarty, R. D., and Friend, D. G., Thermophysical Properties of Helium-4 from 0.8 to 1500 K with Pressures to 2000 MPa, NIST Technical Note 1334, Boulder, Colo., 1998. The source for thermal conductivity is Hands, B. A., and Arp, V. D., A Correlation of Thermal Conductivity Data for Helium, Cryogenics, 21(12) 697-703,1981. 

Here Phc = PHe(P> T) is the density of the helium gas which can be determined from measured data of pressure (p) and temperature (T) normally by using the ideal gas equation of state (EOS) or a standardized real gas EOS [1.45]. 

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